E-rhic-ir-l mailing list

["Montag, Christoph" <montagc AT bnl.gov>]

The vertical emittance used by Charlie is half the horizontal design emittance, which corresponds to a fully coupled machine. This means it's 10 or 12nm, which is larger than the vertical design emittance in most cases. Assuming the design emittance is 4nm, this gives us about 23 sigma aperture if we get 15 sigma with a 10nm emittance.

I highly doubt that a vertical emittance if 10nm is viable in terms of polarization. I really would like that value to come down to 5 or at most 6nm.

Christoph

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From: E-rhic-ir-l <e-rhic-ir-l-bounces AT lists.bnl.gov> on behalf of Drees, Angelika via E-rhic-ir-l <e-rhic-ir-l AT lists.bnl.gov>
Sent: Friday, June 12, 2020 4:37:21 PM
To: Hetzel, Charles <chetzel AT bnl.gov>; Palmer, Robert <palmer AT bnl.gov>; e-rhic-ir-l AT lists.bnl.gov <E-rhic-ir-l AT lists.bnl.gov>
Subject: Re: [E-rhic-ir-l] sigmas of vertical apertures in IR regions

 

Bob,

sorry, probably dumb question: we were talking about electrons? What do you mean with 275 GeV (which is the proton energy)? A

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From: E-rhic-ir-l <e-rhic-ir-l-bounces AT lists.bnl.gov> on behalf of Palmer, Robert via E-rhic-ir-l <e-rhic-ir-l AT lists.bnl.gov>
Sent: Friday, June 12, 2020 4:18 PM
To: Hetzel, Charles <chetzel AT bnl.gov>
Cc: List (E-rhic-ir-l AT lists.bnl.gov) <E-rhic-ir-l AT lists.bnl.gov>
Subject: [E-rhic-ir-l] sigmas of vertical apertures in IR regions

 

I was trying to say that, from Mike Sullivan’s work we expected a larger vertical electron tail than horizontal. The maximum that would fit in the currently round focusing magnets at the IP turns out to be 23 sigma vertical, rather than the 15 sigma horizontally. This was assuming, at 275 GeV, a horizontal emittance of 24 nm, and a much smaller vertical emittance. As Christoph pointed out, you had been using a symmetric emittance,  of, was it 40 nm? In any case far larger than the actual beam in that case. So you probably have plenty of aperture. But we need to get this straight to avoid later heart attacks, and we need to do this for all the energy cases including 5 GeV with vertical emittance 10.2 nm and horizontal 20 nm.

 

Bob.